A Beginner's Guide to Selecting Your First Pet
by AkitaFallow
Summary: Gladstone was not a dog. Nor a cat, or a fish, or any other conventional pet. Honestly, John still wasn't sure what sort of creature Gladstone really was, but he certainly remembered thinking he'd had a bit too much to drink when he came home to find it lying on the sitting room carpet.


John Watson had encountered many things upon his return to 221B Baker Street at the end of each day. He'd discovered a head in the fridge, fingers in the pickle jar, a hand in the freezer. He'd been rendered speechless by the strangest possible sounds tortured from a poor violin, and heard full monologues to a skull. He'd opened the door to gunshots, fires, explosions, shouting matches, angry sibling staring contests and, on one memorable, panic-inducing occasion, absolute and utter silence.

But never in all his years would he have expected to come home to this, and living with Sherlock Holmes had made him amenable to almost everything.

His first clue should have been the slightly blackened corner of the flat door, or the rumpled, somewhat singed rug on the first landing. Even if he missed both of those, the odd snuffling sounds coming from the other side of the door should have made him pause for a moment. He should have spared a thought to the fact that there was no possible way a sane Sherlock (which was a relative term in and of itself) would be making any noise similar to that.

But he didn't register any of these things. And so, when he pushed open the door and was met with what was probably the strangest sight he had ever seen in his life, he reacted in the way anyone who'd been living with Sherlock Holmes for as long as he had would.

He stopped, laid his hand on the doorframe, planted his feet firmly outside of the threshold, closed his eyes for a moment, and took a deep breath.

"Sherlock. What the _bloody hell _is that?"

His flatmate blinked up at him from the sofa with that deceptively innocent gaze that always—without fail—managed to put John on edge. Because an innocent Sherlock was a Sherlock that was moments away from revealing something entirely unpleasant. "What's what, John?"

John kept his feet firmly planted by the door. "_That_," he said forcefully, gesturing at the _thing_ lying in the middle of his sitting room carpet.

Sherlock glanced over the top of his—no, actually, that was John's—laptop screen and down at the floor disinterestedly. "Ah. Not sure."

"You..." John's mouth worked in silence for a moment. "You're not sure." His voice was flat with disbelief.

"I'm still working on it," Sherlock groused defensively. "I've managed to ascertain that it's not a giant scorpion. Nor is it a crab, though it shares a vague physical likeness."

"Wait. You're _researching _what it is while it's lying almost catatonic on our carpet? For God's sake, Sherlock, what if it attacks you? Or, more importantly, what if it attacks _me_?"

Sherlock waved a hand dismissively, eyes still fixed on the screen. "Don't be ridiculous, John. It hasn't exploded in fire in at least forty minutes."

John closed his eyes again in the vain hope that maybe this whole issue would be gone when he opened them again.

He should have known better.

"_Please_ tell me you didn't just say that this thing breathes fire," he said slowly.

Sherlock scoffed. "Of course not." John's relief was short-lived when his flatmate continued, "It expels it from its abdomen in a small explosion. Fascinating, really. It should be physiologically impossible, but I witnessed it myself twice."

John opened and closed his mouth twice before pursing his lips and rubbing his chin. "Sherlock." He repositioned his feet slightly, carefully forming his response in an attempt to avoid saying something he might regret. "Sherlock. _What_ the _bloody hell _do you think _you're DOING_?" Well. Shouting hadn't been his goal, but he supposed it was better than a more... _physical_ response.

The... _thing _on the floor twitched slightly before continuing its absent snuffling of the carpet. One of its pincer-like limbs waved lazily in the air while the other five lay limp on either side of the three-foot-long shell that was its body.

Sherlock finally looked up from the laptop screen and regarded his flatmate with raised brows. "Really John, there's no need to shout. I can hear you perfectly."

John clenched his fists by his sides, taking a deep breath through his nose.

"I am researching."

John opened his mouth, paused, and put a finger to his lips to stop himself from saying something he'd regret. After a moment, he trusted himself to speak. "Yes. You said that."

The crab thing made a strange wheezing sound and seemed to sink into the carpet, almost like a contented sigh. John carefully stepped back against the wall and placed a hand on the door frame, trying to properly ground himself in this new, bizarre situation.

Sherlock continued to type.

"You thought it would be a good idea to just leave it lying there?"

Sherlock gave him a supremely flat look. "I am not nearly strong enough to move it when it is so inclined to stay, John."

"And so it wandered into the flat and you, what? Let it nap on the sitting room carpet?"

Sherlock scoffed. "I hardly did _nothing,_ John. I am performing several delicate experiments in the kitchen, and I couldn't very well allow it to destroy the flat entirely."

John waited a moment for a longer explanation, but the silence (broken only by the thing's snuffling and his insane flatmate's typing) pressed on for several seconds until he realized he would have to do this the hard way.

"Please," he said with false cheerfulness as he gestured casually with a hand, "explain how you subdued the angry beast with your superior intellect."

"So glad you asked, John!"

John was always slightly disappointed when his sarcasm was so bluntly ignored.

"It was simple, really. The stench of sulphur was strong from the moment it came through the door, and only increased when propelled itself with its explosions—" The gesture toward the kitchen made John feel very, very wary to actually set foot in there, because he had no idea how he would deal with the probable destruction, "—so I came to the very sensible conclusion that its explosions are, of course, sulphur based. Much of its aggressive nature seemed to stem from such explosions, so the obvious solution was to neutralize the explosions. Of course, the most stable compound was, I surmised, Epsom salts, which can be rather easily created with magnesium oxide and sulphur. As a doctor, you of course kept a small supply of magnesium oxide in the upstairs bathroom, which was extremely helpful. The problem, then, was forcing the beast to consume it, as it doesn't have any visible mouth or other orifice. After some study, I found that it has what appear to be suckers similar to those of leeches along its underside, and so concluded that it likely consumes blood. Fortunately, I had several litres of cow's blood in the refrigerator, which it seemed to enjoy quite thoroughly." He gestured at a large brown spot in the middle of the carpet, and John hoped to God that it wasn't what he thought it was. "The magnesium oxide took effect immediately, and it has been quite calm and content since."

John tried so very, very hard to pretend none of this was happening, and failed once more.

"…You gave it an antacid, mixed with _blood_ _that you poured on the carpet_, and hoped it would calm down."

"Essentially."

"And it worked."

"Clearly."

"So the fact that you're good with chemistry is the only reason the flat is still standing."

"Quite possibly."

John was almost surprised he made it to his room before the hysterical laughter (and maybe a few tears, he honestly couldn't tell) could begin in earnest.

* * *

"We can't keep it here."

"Nonsense. It's perfectly calm, and seems to stay so as long as it is provided with a steady diet."

"But _blood_ and _antacid_, Sherlock?"

"Both are simple enough to acquire in our professions."

"Are you _insane_?"

"I can't very well make it do anything it doesn't want to do, John. It weighs well over a hundred kilograms and is quite fond of the carpet. I do not anticipate a favourable reaction should it be moved."

"We don't even know what it _is_! Are you going to entertain clients with a bloody great _exploding crab_ in the middle of the floor? 'Oh, I'm quite sorry, Mrs Bradbury, Gladstone is having an off day, don't mind the explosions, they're normal!'"

"Gladstone? That's a very fitting name."

"Oh, for—Sherlock! We are _not _naming it! We're not keeping it! What would we do with it? What would Mrs Hudson say?!"

"She seemed fairly indifferent when she brought in the tea several hours ago."

"…She didn't mind."

"Indeed. She seemed quite content to ignore its presence entirely."

"That's because she probably thought she was _insane_."

"John. Be rational. We could study this creature as it grows. Think what kind of potential an undiscovered species could have!"

"And when the government comes looking for its genetic experiment?"

"Mycroft would already be knocking on the door were that the case."

"What if it gets bigger?"

"The second bathroom is perfectly suited to such things. And there is always 221C; Mrs Hudson wouldn't mind another tenant."

"No."

"John, think—"

"_No._"

* * *

A week later, Gladstone the fire-crab-thing was comfortably enclosed in the main floor bathroom with a large supply of cow's blood and magnesium oxide, and John Watson was wondering exactly had become of his life.

* * *

Hundreds of kilometres north of London, Rubeus Hagrid opened his most recent crate of Blast-Ended Skrewts from the British Department of Mysteries and discovered that there were four instead of the five he'd left with.

"…Oh dear."

_**FIN**_


End file.
